The present invention provides composite materials comprising at least two different plastic material layers directly bonded to one another, of which one layer consists of polyurethane and the layer directly bonded to it consists of a different thermoplastic plastic material.
It is known that composites comprising a thermoplastic material and a polyurethane, in particular a polyurethane foam, do not exhibit adequate bonding adhesion. This bonding adhesion can be improved by the use of adhesion-promoting layers. This approach is, however, undesirable for applications in the automobile industry, where such composite materials are increasingly being employed, because the required working-tip and recycling processes entail the use of materials which preferably differ as little as possible.
Therefore, the object of the present invention was to adequately improve the bonding adhesion between a layer made of a polyurethane and a layer directly bonded thereto made of another thermoplastic material.
This object is achieved according to the invention by the provision of a composite material consisting of at least two layers directly bonded to one another, comprising
A) at least one layer comprising a polyurethane formed by the reaction of (a) at least one polyisocyanate, with (b) at least one isocyanate-reactive component, and
B) at least one other (or second) layer which is directly bonded to the polyurethane layer A), and which comprises a thermoplastic plastic material that is different from the polyurethane layer A),
wherein layer A) has a residual content of reaction components containing ether groups of no more than 400 ppm, and preferably of no more than 100 ppm, which result from the polyurethane preparation.
This content of reaction components which contain ether groups are isocyanate-reactive components which did not react with the isocyanate component in the preparation or formation of the polyurethane which forms layer A).
The polyurethanes or polyurethane ureas used in accordance with the present invention as layer A) are obtained by the reaction of one or more polyisocyanates, with one or more polyfunctional compounds containing isocyanate-reactive hydrogen atoms, preferably polyols.